NEW YORK, June 2 -- Authorities said Saturday that they had broken up an alleged terrorist plot to bomb aviation fuel tanks and pipelines at John F. Kennedy International Airport, arresting a former airport worker and two other men with links to Islamic extremists in South America and the Caribbean.

The lone U.S. resident and alleged leader of the conspiracy, Russell Defreitas, 63, a native of the small South American nation of Guyana, was arrested in Brooklyn. Two others -- one of them a former member of parliament and religious leader in Guyana -- were being held abroad, and a fourth man was being sought by authorities overseas.

The plot did not get beyond the planning stages and had no apparent direct links to al-Qaeda or other Middle Eastern terrorist groups, according to officials and documents released Saturday. But officials said its international scope and the sensitive nature of the target -- one of the United States' busiest airports and a key lifeline between New York and cities worldwide -- caused them to move quickly to secure the arrests.

U.S. Attorney Roslynn R. Mauskopf described the plan at a news conference here Saturday as "one of the most chilling plots imaginable," adding that "the devastation that would be caused had this plot succeeded is just unthinkable." The complaint charging the four men quotes one predicting that the attack would cause "greater destruction than in the Sept. 11 attacks."

Authorities noted that the cell had not targeted passenger terminals or airplanes. Officials and airport security experts said that an explosion at the cell's primary targets -- JFK's fuel tanks and a small segment of the 40-mile petroleum pipeline that supplies the airport -- probably would have resulted in major damage but relatively limited loss of life.

Nonetheless, the charges provided yet more evidence of the threat posed by homegrown terrorists, embittered extremists who hail from the Middle East or, in this case, from the Caribbean and northeastern South America. Less than a month ago, authorities announced that they had broken up a cell of Muslim militants, most of them ethnic Albanians, who were developing a plot to attack soldiers at New Jersey's Fort Dix.

The new case, officials say, also shows how extremists in the United States can use the Internet to reach out for help, domestically and internationally, to turn their rage into an assault.

"The defendants sought to combine an insider's knowledge of JFK airport with the assistance of Islamic radicals in the Caribbean to produce an attack that they boasted would be . . . devastating," Kenneth L. Wainstein, assistant attorney general for national security, said in a statement.

For New York, the epicenter of the Sept. 11, 2001, attacks, the arrests were another reminder that the city appears to remain the primary U.S. target for terrorist attacks.

The alleged conspirators, authorities said, were initially detected via information gathered by the CIA in South America and the Caribbean, home to Jamaat Al Muslimeen, an extremist Black Muslim group that tried to overthrow the Trinidadian government in 1990.

That led federal and local authorities in the New York region to launch a 16-month sting operation focused on the activities of Defreitas, a naturalized American citizen who worked for years for a small airline company based at JFK. According to the complaint, he appeared to harbor deep resentment against the United States that dated to before the 2001 attacks.

The document alleges that he surveilled the airport four times in January, focusing on fuel tanks, noting security precautions and reviewing an escape plan. What Defreitas apparently did not know was that one of the plotters with him much of the time was a law enforcement informant who recorded much of what he said.

The four men allegedly planned to disable the airport control tower from which security officials monitor fuel tank locations, and then use two explosions to blow up the double tanks and provide enough oxygen to ignite the fuel inside.

Defreitas described a cell of six participants, according to the complaint. However, the plot never reached an "operational stage" that put the airport in any danger, and officials said the cell never succeeded in obtaining explosives.

Also charged are Kareem Ibrahim, Abdul Kadir and Abdel Nur. Ibrahim, a Trinidadian, and Kadir are being detained in Trinidad, and U.S. officials are seeking their extradition to New York. Kadir is a former member of the Guyanese Parliament and a former mayor of Linden, Guyana. Nur, a Guyanese national of Pakistani descent, is still at large.

If convicted of conspiring to attack the airport, they would face a maximum sentence of life in prison.

The complaint alleges that the four men tapped into an international terrorist network, utilizing its knowledge, expertise and contacts to devise the plot and to obtain operational support and capability to carry it out.

The complaint alleges that Defreitas traveled several times to meet with Kadir and Nur in Guyana, and later with Ibrahim in Trinidad, seeking financial and technical assistance.

Guyana and the island nation of Trinidad possess small but relatively influential Islamic communities. Both countries also stand out because of their sizable South Asian populations.

In 1990, Jamaat al Muslimeen held the prime minister of Trinidad and members of parliament hostage for five days while rioting and looting occurred in Port-of-Spain. After a long standoff, Jamaat leader Yasin Abu Bakr and his followers surrendered to Trinidadian authorities but were later granted amnesty.

Officials and industry experts said an attack on fuel tanks and pipelines at JFK could have caused significant financial and psychological damage, but not major loss of life.

The tanks are linked to a pipeline that distributes fuel to sites from New York to Pennsylvania. Buckeye Partners L.P. operates the 40-mile pipeline, which originates in Linden, N.J., where Buckeye receives oil shipments from the nearby Bayway refinery or from tankers unloading at deepwater terminals.

From there it crosses Staten Island and goes underwater to Brooklyn, and travels mostly along the Long Island Rail Road right-of-way to the airport.

Because of their thickness and safeguards, such pipelines are difficult to damage, an official said.

"We have pretty extensive security and safety features on that pipeline system," said Roy Haase, a spokesman for Buckeye, which owns approximately 5,400 miles of pipelines in the Midwest and Northeast.

Haase said that the fuel tanks at the airport are separated from the pipelines by cutoff valves and that even if a fire broke out at the tanks, it would not back up into the pipelines. "The pipeline is completely full of liquid so there's no oxygen in it," Haase said. "To say that the pipeline would blow up is just not possible."

Fuel tanks at airport are in two clusters, removed from main passenger terminals and runways.

An explosion there "may not cause a lot of deaths, but it would be spectacular and seen around world," said John W. Magaw, a former head of the Transportation Security Administration. "It could cripple the airlines."

The last major fuel tank fire at an airport that federal investigators could recall took place in 1990 at Denver's old Stapleton International Airport. It took more than 600 firefighters to extinguish the blaze, which burned for two days and snarled air traffic. More than 3 million gallons of fuel were lost to the fire or leakage from the tanks, at a cost of between $15 million and $20 million, but no one was injured, according to the National Transportation Safety Board.

According to the complaint, Defreitas stressed JFK's symbolic significance as a terrorist target.

"Anytime you hit Kennedy, it is the most hurtful thing to the United States. To hit John F. Kennedy, wow. . . . They love John F. Kennedy like he's the man. . . . If you hit that, the whole country will be in mourning. It's like you can kill the man twice," he said in a recorded conversation with the source.